A mobile device may be generally configured to communicate with a wireless network and may generally comprise a transceiver (e.g., a receiver and a transmitter), a local oscillator (LO), and a mixer. In a radio receiver where a passive mixer coupled with a 25% duty cycle LO implements a translational filter to suppress a transmit signal leakage, the resulting frequency response (e.g., band-pass characteristic) may be asymmetric with respect to the gain at a positive frequency offset and a negative frequency offset from the carrier frequency. In an asymmetric frequency response, the gain difference between the positive frequency offset and the negative frequency offset is an increasing function of the frequency offsets and yields a greater impact at higher signal bandwidths. In a 3G cellular system standard (also known as Universal Mobile Telecommunications System (UMTS) or Wideband Code Division Multiple Access (WCDMA)), the signal bandwidth is not sufficiently large for the asymmetry to be significant. However, in a 4G cellular system standard, the signal bandwidth is higher and a gain imbalance between the positive frequency offset and negative frequency offset of the signal bandwidth may cause significant performance degradation.
For a digitally modulated signal, an asymmetry in the frequency response of the receiver will degrade the modulation accuracy at its output and, thereby, increase the error rate of the communication system. In conventional cellular terminals that transmit and receive simultaneously, a duplexer may be employed to suppress a leakage of a transmit signal into the received signal path. Additionally, further suppression may be required to avoid excessive desensitization of the receiver by the leakage of the transmit signal. However, conventional devices, systems, and methods are insufficient to generate a sufficient symmetric frequency response about a carrier frequency. As such, devices, systems, and methods allowing for the generation of such frequency responses are needed.